Inhibition effects and mechanisms of chlorinated aromatics formation by thiourea [(NH2)2CS] was investigated.

PCDD/Fs, PCBs, and chlorobenzenes were inhibited effectively in the model/real fly ashes in the presence of thiourea after heating at 300 °C.

Multielement characterization using X-ray absorption spectroscopies of copper, chlorine, sulfur, nitrogen, and carbon revealed possible inhibition paths.

Thiourea possibly influenced to sulfidization of the copper catalyst, blocking the chlorination of carbon, and changing the carbon frame.

Thiourea plays a role as a sulfur and nitrogen donor to achieve multiple and synergistic inhibition of chlorinated aromatics.